Many vehicles, such as aircraft, are commonly equipped with one or more vision enhancing systems. Such vision enhancing systems are designed and configured to assist a pilot when flying in conditions that diminish the view from the cockpit. One example of a vision enhancing system is known as a synthetic vision system (hereinafter, “SVS”). A typical SVS is configured to work in conjunction with a position determining unit associated with the aircraft as well as dynamic sensors that sense aircraft altitude, heading, and orientation. The SVS includes or accesses a database containing information relating to the topography along the aircraft's flight path, such as information relating to the terrain and known man-made and natural obstacles proximate the aircraft flight path. The SVS receives inputs from the position determining unit indicative of the aircraft location and also receives inputs from the dynamic sensors. The SVS is configured to utilize the position, heading, altitude, and orientation information and the topographical information contained in the database, and generate a three-dimensional image that shows the topographical environment through which the aircraft is flying from the perspective of a person sitting in the cockpit of the aircraft. The three-dimensional image (also referred to herein as an “SVS image”) may be displayed to the pilot on any suitable display unit accessible to the pilot. The SVS image includes features that are graphically rendered including, without limitation, a synthetic perspective view of terrain and obstacles located proximate the aircraft's flight path. Using a SVS, the pilot can look at a display screen of the display unit to gain an understanding of the three-dimensional topographical environment through which the aircraft is flying and can also see what lies ahead. The pilot can also look at the display screen to determine aircraft proximity to one or more obstacles proximate the flight path.
Another example of a vision enhancing system is known as an enhanced vision system (hereinafter, “EVS”). A typical EVS system includes an imaging device, such as, but not limited to, a visible lowlight television camera, an infrared camera, or any other suitable light detection system capable of detecting light or electromagnetic radiation, either within or outside of the visible light spectrum. Such imaging devices are mounted to the aircraft and oriented to detect light transmissions originating from an area outside of the aircraft and typically located ahead of the aircraft in the aircraft's flight path. The light received by the EVS is used by the EVS to form an EVS image that is then displayed to the pilot on any suitable display unit in the cockpit of the aircraft. The sensor used in an EVS is more sensitive to light than is the human eye. Accordingly, using the EVS, a pilot can view elements of the topography that are not visible to the human eye. For this reason, an EVS is very helpful to a pilot when attempting to land an aircraft in inclement weather or at night. One advantage to an EVS system is that it depicts what is actually present versus depicting what is recorded in a database. However, the EVS system has low resolution and may not be sensitive enough to detect certain obstacles because of their size or other conditions. For example, thin radio towers, high voltage wires, cables, power lines, etc. represent a particularly insidious obstacle hazard, as they are difficult to detect by the EVS system even during daylight with good visibility conditions.
Combined vision displays include both a SVS image and an EVS image and may further include additional images, in the form of symbology. The symbology commonly appears as an icon or a series of icons on the display screen and may be indicative of the aircraft heading, direction, attitude, and orientation. With combined vision displays, the SVS and EVS images are commonly shown to the pilot on the same display screen. The EVS image (which may be smaller than the SVS image) may be overlaid on top of the SVS image such that the portion of the SVS image underlying the EVS image may not be visible or may be obscured (such as when the EVS overlay has a high level of opacity or is semi-transparent, respectively). The EVS overlay in a combined vision display may be visually partitioned into separate portions. The portion of the EVS image below an attitude reference (e.g., the zero pitch attitude for the aircraft) is displayed in a manner that provides a seamless transition to/from the underlying SVS image while the upper portion of the EVS image is displayed in a different color than the lower portion of the EVS image and in a manner that allows the underlying SVS image to be perceived. In this manner, a pilot can quickly and intuitively ascertain the relative attitude and/or relative altitude of the aircraft with respect to the features shown in the EVS image while maintaining situational awareness.
One important aspect of situational awareness is to be aware of obstacles that pose a collision threat to vehicles. This is particularly true for aircraft during take-off and landing or other low altitude operations and even more so in low visibility conditions. Terrain and obstacle images should be presented in such a way that they will provide timely awareness of the type, height, location, and distance of possible collision threats relative to the vehicle. In order to successfully avoid obstacles, the operator will have a short response time in which to determine how best to avoid the obstacles. Unfortunately, obstacle images in combined vision displays, even if within sensor detection range or in the database, may not be easily visible, thereby limiting obstacle awareness and decreasing the potential for obstacle avoidance.
Accordingly, it is desirable to provide systems and methods for enhanced display of obstacles in a combined vision display. It is desired to provide the pilot with heightened obstacle awareness by selectively bringing obstacle images to the front of the combined vision display and visually highlighting the obstacle images, thereby increasing the potential of obstacle detection and avoidance regardless of obstacle size, and other conditions. Furthermore, other desirable features and characteristics of exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.